WEBVTT CHRISTINA, YOU TALKED TO THELEAD DETECTIVE ABOUT THIS LATESTTHREAT.CHRISTINA: RIGHT NOW,INVESTIGATORS HERE AT THEWAUKESHA SHERIFF'S OFFICE AUSING FORENSIC TEAMS TODETERMINE IF THIS LETTER ISREALLY FROM JOSEPH JAKUBOWSKI.>> IT DIDN'T HAVE A RETURNADDRESS ON IT.IT WAS TAPED SHUT WITH A STICKERWITH OUR ADDRESS ON IT. CHRISTINA: MIKE LEDONNE IS THEMANAGER AT THE ACE HARDWARESTORE IN SUSSEX.HE TELLS ME WORKERS AT THE STORERECEIVED A LETTER IN THE MAILTHURSDAY MORNING FROM SOMEONECLAIMING TO BE JOSEPHJAKUBOWSKI, THE FUGITIVE FROMJANESVILLE.>> HE HAD UNDERLINED EASTERSUNDAY SEVERAL TIMES. CHRISTINA: LEDONNE SAYS HISCO-WORKERS IMMEDIATELY CALLEDPOLICE, AWARE OF THE INTENSEMANHUNT FOR JAKUBOWSKI.>> IT WAS A COMPUTER GENERATEDLETTER, BUT IT WAS WRITTEN IN AFONT THAT WOULD APPEAR TO BEHANDWRITTEN. CHRISTINA: LIEUTENANT CARINISAYS THE LETTER HAD A TYPEDSIGNATURE OF JOSEPH JAKUBOWSKI,BUT HIS TEAM OF INVESTIGATORSWERE WORKING WITH FEDERALOFFICIALS TO AUTHENTICATE IT.JAKUBOWSKI'S STEPFATHER TELLS 12NEWS THE 32-YEAR-OLD IS MORELIKELY TO HAND-WRITE A LETTETHAN TYPE ONE.WHOEVER WROTE THE LETTERMENTIONED VIOLENCE TOWARDS ALLCHURCHES IN SUSSEX ON EASTERSUNDAYNOW, AUTHORITIES AREN'T TAKINGANY CHANCES AND ARE WARNING THEPUBLIC.>> THERE ARE A NUMBER OFCHURCHES, SO WE ARE GOING TO DOOUR BEST TO TRY AND MAKE CONTACTWITH THE CHURCHES. CHRISTINA: THE MANAGER AT THHARDWARE STORE TELLS ME HE DOESNOT KNOW JOSEPH JAKUBOWSKI ANDHAS NO IDEA WHY THE LETTER WASMAILED TO THEM. INVESTIGATORSHERE SAY BESIDES THIS INCIDENTTHEY HAVE NOT HAD ANY SIGHTINGSOF THE FUGITIVE IN WAUKESHACOUNTY.JOYCE: CHRISTINA, ANY IDEA WHERETHE LETTER WAS POSTMARKED FROM

A written threat against unspecified churches in the Sussex area was sent via US Mail by someone purporting to be Joseph Jakubowski, the Wisconsin man who authorities say has made anti-religious and anti-government comments and burglarized a Janesville gun shop, Waukesha County Sheriff Eric Severson said in a statement.

"It didn't have a return address on it, it was taped shut with a sticker with our address on it," said Mike Ledonne, the store manager.

Ledonne does not know Jakubowki and has no idea why a letter would be sent to their store, but it did imply acts of violence this weekend.

"Sussex churches were going to get shot up and it was going to be a bloody Sunday for it," said Ledonne.

Jakubowski, of Janesville, has been on the run since April 4 when officials say he broke into The Armageddon Gun Shop and stole 18 weapons and other items before setting his vehicle on fire. A 161-page manifesto he mailed to President Trump has been received by the White House and is still being analyzed, authorities said.

Earlier Thursday, Rock County officials pleaded with Jakubowski to turn himself in, and they urged residents to be extra vigilant during the holy weekend.